The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.
Harvested corn grain is classified into five grades, with the highest quality grade, Grade No. 1, being the most expensive. Classifying corn grain involves classifying a minimum weight per bushel and a percentage of damaged kernels per bushel. Although grain moisture is not used in determining corn grain quality grades, it is used to determine a sales price per bushel of a particular grade. Grain moisture refers to and is measured as the ratio of water mass to wet kernel mass, referred to herein as “wet-basis”. Grain moisture level is important to buyers because the level of moisture in grain can affect the amount of degradation of grain during storage and shipment. Therefore buyers generally request that grain moisture be around 15.5% or less. If a grower harvested corn that has higher than desired grain moisture, then buyers may demand a discount for the harvested corn. The cost may be significant.
For example, the economic impact of a grower who harvested 1000 lbs. of corn with grain moisture of 20% is that the price per bushel would be discounted based upon the harvest weight after drying down the harvest to the desired moisture level. In this case, drying down 1000 lbs. of harvest at a moisture level of 20% to a moisture level of 15.5% would shrink the overall harvest weight to approximately 955 lbs. This loss in total weight would equate to about a 4.5% write-down in value. Therefore the economic impact can be significant if a harvest is not at the desired grain moisture level.
As a kernel grows, the corn plant transfers water and nutrients to the kernel. During maturation the amount of kernel moisture begins to slowly decrease. When the kernel reaches physiological maturity, referred to as R6 stage, there is a passive exchange of moisture between the kernel and outside air. The R6 stage is also referred to as “black layer” because physiological maturity occurs when a black layer forms at the base of the kernels. The black layer is a hard starch layer that turns black or brown and cuts off the water and dry matter transfer to the kernel. Once the R6 stage is reached the decrease in kernel moisture is primarily due to the rate of water loss from the kernel itself to outside air. This rate is referred to as grain dry down.
Grain dry down is influenced by many factors. One such factor is the ambient air temperature and humidity. Higher humidity or cooler temperatures may slow grain dry down because there is less difference between the humidity in the kernel and the ambient air. Conversely, areas where the humidity and/or temperature are low the grain dry down may be accelerated. Therefore growers must account for current and future weather conditions when estimating the ideal harvest time based on grain dry down.
Producers of hybrid corn seeds provide relative maturity ratings to help growers predict when to harvest their grain based upon the environment and the type of hybrid seed. Relative maturity is a method to classify a corn hybrid seed based on the mega-environment where it is planted. Relative maturity is a rating system that helps determine when a hybrid may be safely harvested with minimal harvest loss due to excessive moisture or kernel damage, usually based upon the assumption that grain moisture loss equals about 0.5 percentage points per day. Therefore two days of field drying equals one day of relative maturity. For example, if hybrid A is assigned a relative maturity of 110 and hybrid B is assigned a relative maturity of 114, and if hybrid A and hybrid B are planted on the same day, then it is understood that on average hybrid B has two percentage points more moisture than hybrid A when hybrid A completes its dry down. Growers use the relative maturity data to approximate when to harvest their corn based upon relative maturity values.
Another factor in determining ideal harvest times is determining when R6 begins, as the physical black layer at the base of the kernel is not visible unless the corn is dissected. Therefore growers estimate the beginning of the R6 stage based upon approximations provided by producers and historical observed data of the different hybrid seeds. However, knowing the rate of grain dry down and the approximate start date of R6 is only helpful if growers know the initial grain moisture content at the beginning of R6. Producers and growers approximate average moisture for corn hybrids at about 30%. By using generalized grain moisture content at R6, dry down predictions are prone to error if the starting moisture content is not near the estimated 30%. Individual fluctuations between grain moisture content at R6 for specific hybrid seed varieties may lead to errors when predicting harvest times based upon a target grain moisture content at harvest.